An information terminal device (also called a smartphone) having both a calling function and a computer function as an example of an electronic device having a display is spreading to consumers. Such an electronic device has an appearance in which a display is arranged on one surface of a main body and the size of the screen occupying the casing strongly influences an impression given to the appearance. The tendency of the design in such an electronic device is that the area where the display is exposed on the front surface of the main body is increased, a periphery area in which the casing surrounds the display (also called a “frame area”) is narrowed, and a smart appearance is sometimes formed. Narrowing the periphery area of the display to make it slimmer is sometimes referred to as “narrowing of a frame” of a display panel.
A display panel is divided into a display area where pixels are arranged and a periphery area where a drive circuit and an input terminal are arranged. Narrowing of a frame of the display panel is for reducing the area of the periphery area. Therefore, a technique in which narrowing of the frame by bending an area where the driving circuit and the input terminal are arranged is disclosed. For example, a display device in which a stainless-steel substrate or a plastic substrate having flexibility is used and the substrate is curved at an outer part of a display area is disclosed (for example, see Japanese Laid Open Patent Application No. 2011-209405, Japanese Laid Open Patent Application No. 2012-128006, Japanese Laid Open Patent Application No. 2011-034066, Japanese Laid Open Patent Application No. 2014-197181). In addition, a flexible display panel in which the thickness of a part of the substrate at which the substrate is curved is reduced to make it easier to bend is disclosed (for example, see Japanese Laid Open Patent Application No. 2010-256660 and Japanese Laid Open Patent Application No. 2010-282183).
However, when attempting to bend four sides of a display panel, a problem arises wherein cutting of wiring and damage of a sealing film (occurrence of cracks, peeling and the like) occur at places where the folds overlap.